Such parameters are important in characterizing a cable and can be useful within the framework of wired diagnosis based on a reflectometry procedure.
In particular the lineal parameters determined by virtue of the present invention can be used as the input data of the reflectometry method described in the applicant's French patent application filed under the number FR 1355377.
But they can also be used for other applications which require a knowledge of these parameters, for example they can be employed to simulate a complex network of cables to allow the diagnosis of faults on the basis of this simulated environment.
The invention applies to any type of electrical cable, in particular energy transmission cables or communication cables, in fixed or mobile installations. The cables concerned can be coaxial, bifilar, in the form of parallel lines, twisted pairs, stranded cable or other. The invention can also apply to mechanical cables, for example cables for supporting infrastructures such as an elevator or a bridge.
The lineal parameters of a transmission line are not always known or provided in the cable manufacturer's documentation. Furthermore, the data provided by cable makers do not always enable these parameters to be determined with sufficient precision.
The procedures described in the publications [1], [2] and [3] are moreover known. These procedures present the following limitations. They usually require at least two measurement points on the cable under test, for example a measurement point at the input and a measurement point at the output or two measurement points at the input while modifying, between the two measurements, the load at the input. Furthermore these procedures present the drawback of being sensitive to electrical faults which disturb the measurements of the lineal parameters obtained.
On the basis of a measurement by time-domain or frequency-domain reflectometry, the present invention makes it possible to extract, by a calculation facility, the cable's intrinsic and generic lineal parameters representative of the propagation of an electromagnetic signal within said cable, over a sought-after frequency span which may be wider than the frequency band of the probe signal.
The lineal parameters of a cable are the lineal resistance R, the lineal inductance L, the lineal capacitance C and the lineal conductance G. In the subsequent description these parameters will be designated by the term RLCG parameters.